| 1. Round | 12/09/2020 | SD Ponferradina | - | CD Castellón | 1:2 | ||||
| 2. Round | 19/09/2020 | CD Castellón | - | Málaga CF | 0:1 | ||||
| 3. Round | 26/09/2020 | UD Logroñés | - | CD Castellón | 1:1 | ||||
| 4. Round | 04/10/2020 | CD Castellón | - | CD Leganés | 2:0 |  |
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| 5. Round | 11/10/2020 | CF Fuenlabrada | - | CD Castellón | 1:1 | ||||
| 6. Round | 17/10/2020 | CD Castellón | - | CD Lugo | 0:1 | ||||
| 7. Round | 21/10/2020 | UD Las Palmas | - | CD Castellón | 2:1 | ||||
| 8. Round | 24/10/2020 | CD Castellón | - | Girona FC | 0:1 | ||||
| 9. Round | 28/10/2020 | CD Castellón | - | UD Almería | 1:2 | ||||
| 10. Round | 02/11/2020 | Sporting Gijón | - | CD Castellón | 1:0 | ||||
| 11. Round | 08/11/2020 | Real Oviedo | - | CD Castellón | 4:0 | |
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| 13. Round | 21/11/2020 | Rayo Vallecano | - | CD Castellón | 2:1 | ||||
| 15. Round | 28/11/2020 | CD Mirandés | - | CD Castellón | 1:1 | ||||
| 16. Round | 02/12/2020 | CD Castellón | - | Real Zaragoza | 1:0 | ||||
| 17. Round | 07/12/2020 | RCD Mallorca | - | CD Castellón | 3:1 | ||||
| 19. Round | 19/12/2020 | CE Sabadell | - | CD Castellón | 1:1 | |
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| 20. Round | 03/01/2021 | CD Castellón | - | CD Tenerife | 0:1 |
Spain